Surgical fasteners, or staples, are commonly used in surgical procedures to allow a surgeon to fasten body tissue together without the need for time consuming suturing procedures. The surgical fasteners can be applied to the body tissue by using surgical staplers which operate to install the fasteners one at a time or to apply a plurality of fasteners in succession or simultaneously. The staplers typically include fastener cartridges from which the fasteners are driven into the tissue.
Two-part surgical fastener devices are previously known. Such devices include a fastener member, or staple, which is generally U-shaped in configuration with a pair of prongs, and a retainer member provided with apertures in which the prongs are engaged and latched. The fastener prongs pierce the body tissue from one side and the retainer member latches the prongs on the other side of the tissue. The surgical fasteners, once engaged, are not separable so that, after being inserted into the body tissue, the fasteners cannot be easily removed. Accordingly, two-part surgical fasteners consist of bioabsorbable material which is absorbed into the body tissue.
U.S. Pat. No. 4,060,089 (Noiles) discloses a fastener strip with multiple barbed prongs and a retainer strip with a plurality of longitudinally spaced openings for receiving the prongs.
U.S. Pat. No. 4,402,445 (Green) discloses a two-pronged fastener with a retainer piece.
U.S. Pat. No. 4,506,670 (Crossley) discloses a two-part surgical fastener in which the retainer piece is held to a supporting member by a lug with a frangible member. The prongs of the fastener, upon entering the apertures of the retainer, break the frangible members and push out the lugs, thereby releasing the retainer piece from the supporting member.
U.S. Pat. No. 4,506,671 (Green) discloses the same two-part surgical fastener disclosed in Crossley U.S. Pat. No. 4,506,670.
U.S. Pat. No. 4,513,746 (Aranyi et al) discloses a two-piece surgical fastener in which the fastener portion has two prongs with outer channels for receiving a tissue piercing member. The retainer piece has extensions with apertures for receiving the prongs of the fastener and longitudinally extending expansion slots.
U.S. Pat. No. 4,534,352 (Korthoff) discloses a two-part surgical fastener including a fastener member with prongs having an increased surface area to volume ratio for faster absorption. Various prong cross-sections are disclosed including round, square, cruciform, channel-shaped and a plurality of fins.
U.S. Pat. No. 4,589,416 (Green) discloses a surgical fastener retainer member assembly including a plurality of retainer members linked together in various configurations including straight and circular rows.
U.S. Pat. No. 4,610,250 (Green) discloses a two-part surgical fastener including a fastener member with four prongs which mate with four openings in the retainer member. The two inner prongs are bent toward each other by camming surfaces in the corresponding openings in the retainer member.
U.S. Pat. No. 4,667,674 (Korthoff et al) discloses a two-part surgical fastener including an extended base to improve hemostasis.
U.S. Pat. No. 4,724,839 (Bedi et al) discloses a surgical fastening system including a staple with two legs of circular cross section. Each leg has a tapered, pointed tip with opposed flange portions extending only partially around the circumference of the leg.
U.S. Pat. No. 4,805,617 (Bedi et al) discloses a surgical fastening system including a plurality of receivers arranged in at least two parallel rows and interconnected by a continuous thin layer or web consisting of the plastic material of which the receivers are formed.
U.S. Pat. No. 4,917,114 (Green et al) discloses a two-part surgical fastener which is annular in configuration.
U.S. Pat. No. 4,932,960 (Green et al) discloses a two-part absorbable surgical fastener including fins on the lateral and transverse sides of the prongs for extra strength. The columns of the retainer member have lateral expansion slots.
U.S. Pat. No. 4,994,073 (Green) discloses a skin fastener in which each prong has a triangularly shaped barb which is flat on both sides to minimize body tissue resistance. The fastener includes indentations which align the fastener with rail members inside an ejection chamber of a surgical stapling apparatus.
U.S. Pat. No. 5,089,009 (Green) discloses an inwardly biased skin fastener including two barbed prongs.
In the use of two-part surgical fasteners, there is a tendency for the fastener prongs to buckle as the fastener is driven through the tissue and inserted into the retainer. As a result of the axial forces encountered, the fastener prongs may buckle outwardly in opposite directions relative to each other, or inwardly toward each other. It is also possible that the fastener prongs may tend to buckle in the same direction under axial loads. This tendency of the fastener prongs to buckle has the undesired effect of increasing the force which must be exerted on the fastener to penetrate the tissue and insert the prongs into the retainer. Also, the prongs may become misaligned with the apertures in the retainer thereby increasing the difficulty of inserting the fastener prongs into the retainer. To avoid these drawbacks, it is desirable to provide a fastener structure with prongs of sufficient strength to resist buckling to facilitate the penetration of the tissue by the fastener prongs and to facilitate the insertion of the fastener prongs into the retainer. Also, it is desirable to provide a fastener with prongs of sufficient strength to sustain the axial loads encountered when the fastener and retainer are assembled to hold the tissue together.
In surgery, it is often desirable to place multiple rows of fasteners in stitching procedures. Two side by side rows of fasteners aligned end to end along the lengthwise direction of the fastener, for example, will exhibit greater holding power and hemostasis than a single row of fasteners. To facilitate the placement of multiple rows, it is desirable to have a staple which is as narrow as possible, particularly if the staple is to be applied endoscopically. However, if the fastener is made narrower for a particular length and shape, the fastener prongs become relatively weaker due to the reduced amount of structural material present in the prongs. Accordingly, it is desirable to provide a surgical fastener which is sufficiently narrow to be inserted endoscopically and installed in multiple rows of fasteners without compromising the strength of the fastener prongs.
It is also advantageous to provide a surgical fastener in which the prongs have pointed tips which facilitate the penetration of the fastener prongs into the body tissue and the insertion of the prongs into the retainer. To minimize the penetration force, it is desirable to provide the tip with an arrowhead-like shape which tends to spread the tissue apart rather than to cut through the tissue. Also, it is desirable to design the tip to achieve self-alignment with the apertures in the retainer and to provide uniform latching when the fastener and the retainer are assembled.
Furthermore, a fastener which is adapted to be supported and guided in a fastener cartridge can avoid the problems associated with the misalignment of the fastener prongs with the apertures in the retainer when the prongs are inserted through the tissue into the retainer. Thus, it is desirable to design the fastener prongs to be engaged and guided for movement in the staple cartridge.